By David Biello
(Click here for original article.)

Humans may have been causing climate change for much longer than we've been burning fossil fuels. In fact, the agrarian revolution may have started human-induced climate changes long before the industrial revolution began to sully the skies. How? Through the clearing of forests, which still remains the second-largest source of greenhouse gas emissions from human activity.

Sediment cores from the mouth of the Congo River -- the deepest river in the world -- suggest that
[Published in GreenNews - Read the original article]